President Barack Obama on February 24 vetoed legislation that would have forced the Keystone XL pipeline through by eliminating the need for State Department approval for the project, which crosses the international border with Canada.

More than 400 bison have been slaughtered outside the northern boundary of Yellowstone National Park in Montana as they left the protected area in their customary winter search for food at lower altitudes.

The 10 most prominent environmental stories of 2014 constituted a wide range of events—extreme weather, natural disasters, major administrative decisions and potent activism. Some of the issues were ongoing. Others surfaced for the first time. And still others rose from a slow burn to a sudden burst of headlines.